The invention generally concerns a pressure measurement device for fluids flowing in lines and more particularly concerns a pressure measurement device for fluids flowing in flexible tubing lines of pressure-controlled roller pumps such as peristaltic pumps for use in arthroscopy and urethroscopy.
A device of this type is known previously from DE 3,338,758. The pressure sensor used according to this reference can be a Stethem element, which is provided with a rigid pressure dome with two connections for a flexible tubing line and with a membrane sealing off the pressure dome. The rigid pressure dome with its membrane is pressed against a surface pressure sensor by means of a union nut.
The pressure sensor is introduced on the pressure surface lying opposite the membrane. Semiconductor sensors or wire strain gauges may be used as pressure sensors.
The transfer of fluid pressure via a sterile filter from a sterile flexible tubing setup to a nonsterile pressure sensor by means of an air column is also known. In addition, sterile disposable pressure sensors or resterilizable pressure sensors may be used, through which the fluid flow passes.
As the pressure built up in the body cavity is determined by the pressure sensor and the rpm of the roller pump is controlled, only a limiting device for a maximum pressure value is provided on the inlet side.
It is a disadvantage in conventional pressure measurement devices that the pressure control of the pump fails as soon as the pressure sensor or its evaluating electronic unit displays a first error. Such an error can be, for example, that the pressure sensor indicates a systemic pressure that is too low, although the actual system pressure is considerably higher and thus is dangerous for the patient. With previously known pressure measurement devices there is provided a measurement of the actual pressure without providing a control system determining whether or not the actual measured pressure is also the correct systemic pressure.
When fluid under pressure is transferred through an air column, another error source may be present due to a possible lack of tightness between the sterile filter and the pressure sensor.
In order to configure conventional pressure measurement devices in a more reliable manner, a mechanical overpressure safety device may be inserted in the line. However, this requires additional sterility measures and has the further disadvantage of a possible gumming up of the overpressure safety valve, e.g., when sugar-containing solutions are used. In addition, in the case of an overpressure, the fluid flowing in the line escapes into the atmosphere, whereby a considerable contamination of the treatment site occurs when a patient is treated.
The use of an additional overpressure safety valve, the use of disposable pressure sensors, and the use of resterilizable pressure sensors usually involves an increased labor expenditure, so that use of these items is not economical.